Hybrid Garbage Trucks Saving Miami-Dade Big Money

How “hydraulic hybrid” technology in garbage trucks could someday save municipalities like Miami-Dade County, Fla., millions of dollars.

A garbage man’s average routine may seem pretty boring — stop, pick up trash, go, repeat. But the viewpoint of 20-year Miami-Dade Solid Waste Management employee John Lewis is a bit different — Lewis enjoys a quieter ride in his new Autocar Expeditor E3 hybrid garbage truck, which he considers one of many benefits made possible by emerging hybrid technology.

“The design is the same, and [the truck] is a little bit slower,” Lewis said, “but it’s a whole lot quieter and carries a lot more garbage.”

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While quietly carting trash from his two routes — covering about 30 miles and spanning more than 1,200 homes — Lewis is helping make “hydraulic hybrid” engineering the future of municipal waste disposal.

Hybrid garbage trucks, like the Autocar E3, that Lewis drives are the latest application for an emerging hydraulic-based technology that its developers say can reduce fuel and maintenance costs for municipalities, while also reducing their carbon footprint.

For government agencies, the biggest attraction might be the promise of cost savings. According to Danny Diaz, fleet manager director of Miami-Dade’s Solid Waste Management Department, the new vehicles are saving so much money that he hopes to convert his fleet to all-hybrid within the next 10 years.

Hydraulic Partnership

A prototype of the hydraulic hybrid vehicle was given in April 2010 to Miami-Dade County — one of three districts in southern Florida now using Autocar Expeditor E3 trucks to collect waste. The goal was to help the hybrid system manufacturer, Parker Hannifin, fine-tune its product before launching it into mass production this month.

The perfect place to test it out was Miami, home to one of the largest municipal waste fleets in the country.

“[Parker Hannifin] wanted us to use the truck to see what its performance was like, and what they could improve upon,” said Diaz, who added five more trucks to his fleet last December.

What started as a pilot instead became Parker Hannifin’s first business partnership. The single test truck was enough to convince Diaz — whose 193-truck fleet services 340,000 homes each day — to purchase several more trucks, each equipped with the company’s cutting-edge hydraulic hybrid technology known as RunWise.

How Hydraulic Hybrids Work

The hydraulic hybrid system uses stored hydraulic energy instead of diesel fuel to power the truck during waste collection stops. A hydraulic launch assist system, also known as a parallel hybrid, is bolted onto the truck’s existing power train and connects using an electronically controlled transfer case.

The system stores energy captured during braking and releases that stored energy during acceleration, allowing the vehicle to run without using fuel. The application is most efficient during frequent stop-and-go use, such as trash pickup.

"The more a vehicle stops and starts, and the heavier and bigger it is, the better this technology works," said Vance Zanardelli, manager of Parker Hannifin’s energy recovery unit.

The company claims its system allows for energy savings of up to 70 percent versus nonhybrid trucks. In terms of fuel, that translates to roughly 45 to 50 percent savings over diesel-only vehicles, Zanardelli said.

“One of the biggest advantages [over other hybrid systems] is that it allows you to absorb the energy you’d lose from braking,” he said. “In comparison, a normal hybrid system — like the one you’d find on a Toyota Prius — only recovers about 20 percent of that lost energy. I don’t know of any other hybrid system available today that can give you that kind of savings.”

Hydraulic Hybrid Savings

An upfront investment is required to see those long-term savings. The vehicles are marked up about $100,000 over traditional diesel-only models. But purchasing them is becoming more feasible; this year the U.S. Environmental Protection Agency approved the RunWise system as an emerging technology, which could result in more grants to help counties like Miami-Dade — and other municipalities nationwide — purchase hybrid vehicles.

For cities like Miami and Hialeah, Fla., — which have joined Miami-Dade County in purchasing hybrid garbage trucks — a fleet of hybrids can save millions of dollars, said Diaz. One factor is less spending on fuel. In less than one year, Miami-Dade’s hybrid trucks collected 2,300 tons of garbage and used approximately 4,000 gallons of fuel, according to Diaz’s calculations. When compared to the rest of the diesel-run fleet, that’s impressive: In a similar span from October 2009 to September 2010, traditional trucks used approximately 2.4 million gallons of fuel, which averaged about 12,800 gallons per vehicle.

"We've estimated these hybrids can save us over $1 million in fuel costs in just one year if we go full-hybrid," Diaz said. “That’s huge.”

The savings don’t stop there. Each truck in Diaz’s fleet makes an average of about 1,000 stops per day, which is tough on brakes, he said. Conventional versions require new brakes every three months, but not the hybrids.

"So far, we haven't had to replace the brake pads on any of our hybrid vehicles," Diaz said. "We're looking at having to do it only once each year — and we're hoping those savings can also be applied to tires."

And besides the cost savings, each hybrid hydraulic truck reduces carbon dioxide emissions by as much as 40 tons per year.

All that should be good news for Parker Hannifin, which went public with its technology last week — meaning more municipalities nationwide will have the opportunity to use the hydraulic launch assist system to save money not only on fuel consumption, but also wear-and-tear maintenance.

The savings likely won’t stop at the dump, however. The company is working to install its RunWise system in city transit buses as well as UPS and FedEx fleets.

“This is just the tip of the iceberg,” Zanardelli said. “We’re looking to make a big impact on how cities nationwide save on energy, and to help make the world a better, cleaner place.”